Sediment at the bottom of my sourdough starter?

So a couple things actually and would love advice on any of them! I started my started about 9 days ago and now feed it twice a day. There's always a lot of activity and it doubles in size pretty quickly and then deflates. Is this fine or should it stay slightly risen? It also still has that vinegary/alcohol smell and not the yeast smell I've been told to look out for - will it just take more time or am I doing something wrong?

The main question though is that whenever it rises theres this layer at the bottom that looks inactive compared to the rest of what's happening. I've posted a photo where you can hopefully see it. Has anyone encountered this? Is it fine or what do I do with it? Occasionally I'll feed the starter and it will look like everything is incorporated and bubbling, but more often than not this is what it looks like.

So you can see there's a layer of unincorporated flour and water at the bottom.

Is your starter equal weights of flour and water? Are you stirring it properly each time you feed? What happens if you now stir up to incorporate the stuff at the bottom? Lots of questions, I know. It looks to me like you are not doing anything wrong, but I suspect you may be feeding it a little too often. If it rises again after you stir the bottom in, then that may be a suggestion to feed less or less often.